Reinforced fibre products

Abstract

A process for impregnating a fibrous product, said fibrous product being a fabric woven from reinforcing fibres or a fabric of randomly disposed fibres, with a matrix polymer comprising causing partial impregnation of the fibrous structure by introducing the fibrous structure into a molten composition comprising the matrix polymer and a melt plasticizer for the matrix polymer and subsequently causing substantially complete wetting of the filaments of the fibrous structure by volatilizing the melt plasticizer from the partially impregnated structure at a temperature at which the polymer is molten, the melt plasticizer being thermally stable at the temperature of the melt and having volatility characteristics such that the plasticizer can be removed below the decomposition temperature of the melt but sufficiently involatile at the temperature of the melt to permit the viscosity of the melt to be reduced by comparison with the melt viscosity of the polymer at the same temperature. When a woven fabric is employed thermoformable composites can be obtained having short beam shear strength values at least 0.7 times the tensile strength of the plastics matrix material of the composite.

We claim: 
     
       1. A fibre reinforced, thermoformable, plastics composite containing at least 30% by volume of reinforcing fibres comprising reinforcement in the form of a fabric woven from reinforcing fibres characterised in that the short beam shear strength of the composite as determined by ASTM Standard D-2344 using a sample span:thickness ratio of 5:1, is at least 0.7 times the tensile strength or yield strength of the plastics material forming the matrix of the composite. 
     
     
       2. A fibre reinforced thermoformable plastics composite according to claim 1 wherein the flexural modulus and flexural strength values of the composite are at least 0.8 times the theoretical reinforcement values. 
     
     
       3. A fibre reinforced thermoformable plastics composite according to claim 1 wherein the flexural modulus, flexural strength, short beam shear strength and impact strength values are at least 0.8 times the values for a comparable composite of the same composition except in that the reinforcement comprises a cross ply lay up of prepregs containing continuous collimated fibres. 
     
     
       4. A fibre reinforced thermoformable plastics composite according to claim 1 or 2 wherein the form of continuous product is at least 10 meters in length.